ci: Add missing Android NDK paths

azure-pipelines.yml

@@ -8,6 +8,10 @@
   # For release conditions
   IsReleaseBranch: $[or(eq(variables['Build.SourceBranch'], 'refs/heads/master'), startsWith(variables['Build.SourceBranch'], 'refs/heads/feature/'), startsWith(variables['Build.SourceBranch'], 'refs/heads/release/'))]
 
+  ANDROID_NDK_HOME: C:\Microsoft\AndroidNDK64\android-ndk-r16b
+  ANDROID_NDK_PATH: C:\Microsoft\AndroidNDK64\android-ndk-r16b
+  AndroidNdkDirectory: C:\Microsoft\AndroidNDK64\android-ndk-r16b
+
 jobs:
 - job: Windows # Build UWP/Android/NuGet
   strategy: